1. Field of the Invention
The present invention relates to a printing apparatus configured to reserve print data transmitted from a host computer and print the print data in response to acceptance of an operation via an operation unit in the printing apparatus from a user, and a print control system.
2. Description of the Related Art
A print control system has been known in which a printing apparatus stores print data transmitted from a host computer such as a personal computer (PC) without immediately printing the print data and which performs print processing when a user performs an operation for performing printing in front of the printing apparatus. In such a print control system, when the user inputs a correct password or the like on an operation screen of the printing apparatus, printing based on the print data can be performed. Such a print control system is effective when a user uses the printing apparatus, which is a common printer connected to a network, and does not desire others to see a print product.
The host computer may designate the number of print copies of a print product and sorting processing (processing for discharging the print products to a sheet discharge unit in the printing apparatus while sorting the print products by the number of print copies) to issue an instruction to perform printing. In this case, if the printing apparatus performs the sorting processing, images on all pages included in the print data are required to be stored in a memory of the printing apparatus, and the memory of the printing apparatus may be weighed down by the data. If the printing apparatus has a limited memory capacity for storing print data, therefore, a method for transmitting and receiving print data has been known, as discussed in Japanese Patent Application Laid-Open No. 2001-216125. According to Japanese Patent Application Laid-Open No. 2001-216125, a host computer generates a plurality of print data pieces by the designated number of print copies, and the generated print data pieces are sequentially transmitted from the host computer to a printing apparatus. When the print data pieces generated by the number of print copies are thus sequentially transmitted to the printing apparatus, all image data pieces on the first page to the final page are not required to be cached in the memory of the printing apparatus.
If the plurality of print data pieces generated by the number of print copies is transmitted to the printing apparatus and is reserved in the printing apparatus, as discussed in Japanese Patent Application Laid-Open No. 2001-216125, the generated print data pieces are required to be transmitted after adding an identical password thereto. A system including a host computer configured to sequentially transmits to the printing apparatus a plurality of print data pieces, to which an identical password is added and which is generated by the number of print copies, and a printing apparatus having a limited memory capacity for reserving the transmitted print data has the following issue. When the host computer transmits print data pieces exceeding the capacity that the memory of the printing apparatus can reserve, the host computer waits until the memory of the printing apparatus becomes empty to transmit the print data beyond the limited memory. At this time, at least one of the plurality of print data pieces generated by the host computer is reserved in the printing apparatus, and the remaining print data pieces are reserved in the host computer (the transmission of the print data is waited for).
In such a state, when a user inputs a correct password on an operation screen of the printing apparatus to perform a predetermined printing operation, printing based on the print data stored in the printing apparatus is performed. When the printing ends, the print data stored in the printing apparatus is erased. When the print data is erased, the remaining print data that waits in the host computer is transmitted to the printing apparatus. The remaining print data that has been transmitted is stored in the printing apparatus, and continues to be stored in the printing apparatus until the password is input again. In such a case, even if the print processing is based on the print data pieces to which the identical password is added, a series of processing from input of the correct password in the printing apparatus to printing based on the print data is intermittently performed multiple times. In addition, the user needs to input the password many times in the printing apparatus, so that the usability is not good for the user.
A similar issue also occurs when an event to erase print data stored in the printing apparatus (e.g., an event to erase print data when a time-out time has elapsed or an instruction to erase a job by a user) is generated. When the event to erase the print data occurs, the event to erase the print data is inefficiently generated many times.